The idlers employed to support the forward ends of endless tracks of track-type tractors are subjected to severe impact loads and to a high rate of wear during tractor operation. The problems occasioned thereby are extensively discussed in U.S. Pat. No. 3,771,843, assigned to the assignee of this application. Replacement of such an idler requires dismantling of the endless track and thus necessitates a substantial "downtime" of the vehicle. In addition, various governmental regulations require a substantial suppression of the noise level normally prevalent during tractor operation.